<body>
    <style>
        .box{font-size: 50px;color: green;}
    </style>
</head>
<body>
    <div class="box" style="width:100px;height:200px;background: red;">
        hello
    </div>
</body>
  <script>
    var obox=document.querySelector('.box');
    console.log(obox.style.height);
    console.log(obox.style.width)
    console.log(obox.style[2])
  </script>